Underreamer



n March 8, 1938. H. c. SMITH UNDERREAMER Filed May 29, 1936 2 Sheets-Sheet 2 /NVEN TOPJ,

Patented Mar. 8, 1938 UNiTE STA@ PT FFE@ Application May 29,

7 Claims.

This invention relates to underreamers, and particularly to that class of underreamers opern ated by rotary apparatus.

The use of underreamers in the oil well indu,.-

try is well understood, particularly where forma tion is to be cut a size larger than the drilling tool. The necessity for enlarging a well hole results where it is desired to cement baci; of a casing and also where casing shoes are used which are, of necessity, larger than the drill.

An object of the present invention is to provide an underreamer wherein cutter members are out oi casing engagement while the underreamer is being lowered through a casing, and then moved into formation engagement at the will of the operator, the operative control being at the surface of the well hole.

Another object is the provision of an hydraulically controlled underrearner, the hydraulic con trol being such as to actuate positive mechanical means in turn directing cutter members of said underreamer into formation engagement.

Another object is the provision of an under'- reamer which may have the cutter elements thereof controlled from the surface of the well, hydraulically, and in such a manner that the diameter of the reamed hole may be varied.

Another object is the provision ci an underreamer having few parts, simple of construction, positive in operation, which may be readily assembled and disassembled, which permits any broken parts to be easily removed, and is generally superior to underreamers now known by the inventor.

Another object is the provision of an underreamer not dependent for operation upon the use of springs for expanding cutters.

Another object is the provision oi an underreamer which may be readily passed through a casing without the cutters injuring the casing or in turn the casing injuring the cutters.

Other objects and uses of the invention will readily suggest themselves to those skilled in the art, and with the above set forth objects, including simplicity of structure, inexpensiveness in cost of manufacture, in view, the invention consists in the novel and useful provision, formation, construction, association, and relative arrangement of parts, members and features, all as shown in a certain embodiment in the accom-- panying drawings, described generally, and more particularly pointed out in the claims.

In the drawings:

Figure 1 is a fragmentary sectional View of a well hole within which is received the improved 1936, Serial No. 82,483

(Cl. Z-75) underreamer, the underreamer cutters being in formation engagement below the well casing,

Figure 2 is an enlarged fragmentary Vertical sectional View of the underreamer within well casing,

Figure 3 is an enlarged fragmentary vertical sectional View, the underreamer cutters being below the lowermost end of the casing and in formation engagement, and,

Figures 4, 5, 6 and 'l are sectional views on the lines 4 6, 5 5, 5 5, and 'I 'l of Figure 2,respectively.

Referring now to the drawings, I is the underreamer as an entirety, and the same includes a body 2 provided with a central bore 3, both ends* of the body being reduced as to external diameter, as indicated at fi and 5, the end il being formed with a pin, indicated in dotted lines in Figure l at 6, and the opposite end 5 being formed with al threaded box shown in dotted lines at 1. in the present instance, the body is provided with longitudinally extending peripheral grooves, channels or troughs three grooves, channels or troughs equidistantly spaced apart being provided for the present underreamer, as best illustrated in Figures 4 to 7, inclusive. Each groove is so formed that a cross section through the body defines a curved bounding wall. This curvature is necessary in order that certain other ele-- ments of the invention, to-wit, the cutters, may be confined within the groove or grooves. Arcuate end walls 9 and Il! form the termini for each groove 8.

As all the grooves are identical in construction, and the mechanism for placement within the grooves is likewise identical, only one groove rwith its mechanism will be described, the same numerals of reference applying in each case.

Referring more particularly to Figures 2 and 3, a series of cutter rollers II, I2 and I3 are mounted upon a shaft I4. The cutter rollers may progressively vary as to external and inn ternal diameter; for instance, in the present case, the cutter roller III is of lesser external and internal diameter than the roller It or i3, and` the same is true for the roller I2 with respect to the roller I3. The shaft I4 is formed with eccentric step portions I5 and I5 to accommodate the rollers I2 and I3. The eccentricity of the portions I5 and I5 is with respect to the axis of the por*` F tion I'I of the shaft. Forming an extension of the shaft I4 is a threaded shank I8, the axis of which lies in the axis of the portion Il of the shaft. The threads are of the double square type and the helical angle is preferably at a degree adapted to rapidly turn the shaft when the said threads engage internal threads of a member to be described. In the present instance, the helical angle of the threads is substantially 45. The threads of this shank cooperate with member I 9, which is internally provided with double square threads 20. The member IS co-operates with member 2 I. This member has one face 22 thereof curved to accommodate the same within the curved portion 9 of the groove, and when so positioned, may be secured to the body by spot welding or by other suitable means, as shown at 23. The member 2| is under-cut at 24, and the member IS is provided with a lug or tongue 25 adapted to t between the wall bounding the groove 8 and within the underecut portion 24 of the member 2l. The member QI is provided with a transverse bore 36 and the lug 25 is formed with a threaded bore 21, which said bores are in' alignment when the members I3 and 2i are cooperating, as shown in Figures 2 and 3. A screw 28 may be passed through the bore 25 and have threaded engagement With the threaded bore 2?. Thus, the two members are held in locked engagement. Reference to Figure 4 shows that side thrust of the members I9 and 2i is effectivelyY resisted by the said members closely engaging the wall bounding the groove 3.

The portion il of the shaft I4 is threaded at 29, and a sleeve 3G in part surrounds the part I? of the shaft I4 and is threaded at 3I for engagement with the threads 2S. The said sleeve which forms what will be termed a piston is fitted within a bore 32 of a block 33. This block carries at one end a tongue or lug 34 adapted to be received within a cut-away portion 35 of a member 35. This member is similar in construction to the member 2l, in that it is provided with a transverse bore 31, which is adapted to align with a threaded bore 38 in the bore 35, whereby a threaded screw 33 may be passed through said bore 35 for threaded engagement with the threads 38. This block 36 is conveniently held to the portion Ill by welding, as indicated at 4I). The member 33 is provided with a transverse bore ill, which is adapted to communicate with a port or bore 42 formed in the body 8 and opening within the central bore 3 of the body.

For convenience of description, the members 2l and 33 may be hereinafter designated as end supports. The block 33, termed a cylinder, and the block I9 together with the screw shank i8, is mechanical means for rotating the shaft when the shaft is moved in one direction.

The operation, uses and advantages of the invention just described are as follows:

I assume, of course, that the present underreamer is provided with three equidistantly spaced-apart sets of roller cutters so that there is a normal balance without undue side movement when the underreamer is in actual use. The cutters are in the position shown in Figures l and 2 when the underreamer is passing through the well casing 43. It will be observed that the peripheries of the cutter teeth are out of engagement with the inner surface of the casing. The cutters are supported one upon the other, the lowermost cutter Ii having its base resting upon the upper end of the sleeve 39 and a portion of the block 33. This position is maintained due to the fact that the portion I5 of the shaft carries an integrally formed or otherwise secured flange 44 which bears against the top of the uppermost cutter I3. It is intended that the cutters II, I2

and I3 should rotate freely upon their respective shaft portions I4, I5 and IS.

The underreamer may be conveniently lowered within the well hole by providing the usual box coupling 45, the pin l of the underreamer being secured within one box, and the lower end of drill pipe 4S secured to the other box. As usual, a bit of some character, such as the iishtail shown at 4l, may have the pin thereof reecived within the threaded box 7 of the underreamer. reamer cutters are held collapsed within the different grooves until the cutters are below the lowermost end of the casing 43. If hydraulic pressure or flow of mud under pressure is maintained through the drill string and the underreamer outwardly through the openings 48 of the shtail bit, a portion of said mud under pressure will enter the ports 42 into the bores 4I and exert a pressure against the pistons which, as be fore stated, includes the lower end of the shaft I4 where it is in threaded engagement withv the sleeve 3B. This pressure will force the pistons upwardly within the bores 32, forming the cylinders of the blocks 33, and in so doing, the external threads I8 will travel within the internal threads 2li of the members I9, resulting in a turning of the shafts I4. As the portions i5 and I6 of the shaft are eccentric to the portion I4, the cutter rollers will be moved into engagement with the formation below the end of the casing, in the manner illustrated in Figure 3. Furthermore, the cutting will be in stages; for instance, the cutter i i will not engage the formation as deeply as the following cutter i2, and the same is true with respect to the cutter i3. This renders cutting easier and more positive, with less likelihood of the underreaming operation resulting in a crooked hole. It is evident that the degree of pressure maintained within the drill string and outwardly of the bit 47 will directly control the pressure engagement or" the cutter rollers against the formation until open or fully expanded. Hence, the operator at the surface of the well hole may determine by the action of the rotary table during rotation of the drill string and the reamer, the degree of cut required.

When it is desired to withdraw the underreamer from the well hole, pressure may be relieved through the drill string which will, of course, relieve pressure from within the cylinder portion of the block 33, with the result that when the tapered end teeth of the cutter' roller i3 engage the lowermost portion of the casing, the shaft I4 will be rotated by the threads I3 moving relative to the internal threads 23 of the block I9 until such time that the cutter may move within the confines of the casing, which will substantially bethe position for all of the cutters depicted in Figure 2.

I claim:

l. An underreamer including an annular body formed with a peripheral groove, a cutter, and a shaft having threaded engagement with the body and eccentrically carrying said cutter and normally maintaining the cutter within the confines of said groove, and hydraulically operated means for moving the shaft longitudinally and rotating the same by reason of its threaded engagement with the body to project said cutter outwardly from said groove.

2. An underreamer including a body having a curved periphery and a central bore and provided with a longitudinally extending groove opening inwardly of the periphery thereof, a roller cutter, and means in threaded engagement with the The underbody for eccentrically mounting said cutter for connement within said groove and for movement outwardly of said groove and beyond the periphery of the body, and hydraulic means for the rst means to rotate the same by reason of its threaded engagement with the body to project said cutter outwardly of the groove.

3. In underreamer construction, an elongated body provided with a curved periphery and with a central Water course, a shaft carried by the body and defining at one end a piston, a cylinder in communication with the w'ater course of the body and receiving the piston end of the shaft, and means for said shaft to positively turn the same when the piston is moved within the cylinder.

4. In underreamer construction, an elongated body provided with a curved periphery and with a central water course, said body provided with an elongated groove, a shaft carried by the body and dening at one end a piston, a cylinder in communication with the water course of the body and receiving the piston end of the shaft, means for said shaft to positively turn the same when f the piston is moved within the cylinder, and a cutter roller within said groove and eccentrically carried on the shaft, whereby the cutter roller is moved outwardly of and inwardly of the groove when the shaft is rotated.

5. An underreamer including a body provided with a central water course, and provided with a peripheral groove, a cutter roller, and a shaft for eccentrically mounting said roller, said shaft provided with a piston portion, a cylinder member in communication with the water course and receiving one end of said piston, and a screw shank secured to said shaft, a block provided with internal threads for engagement with said screw shank, said block being secured to the said body whereby when fluid is passed through said water course into said cylinder, the piston is moved in one direction and rotated, the said cutter roller being moved outwardly from said groove beyond` the periphery of the body.

6. An underreamer including a body provided with a substantially curved periphery and with a central water course, a block, provided with internal screw-threads, secured to said body within the said groove; a cylinder member within` said groove, a shaft provided at one end with screwthreads for threaded, engagement with the threads of the block, said shaft provided at the other end with a piston portion received within said cylinder, and a cutter roller eccentrically mounted upon said shaft, the relationship being such that uid passed through said water course and admitted into said cylinder will actuate the piston in one direction to rotate said l shaft through the threaded arrangement to in turn move the cutter roller outwardly of said groove.

'7. An underreamer including a body provided with a substantially curved periphery and with a central water course, a block, provided with internal screw-threads, detachably secured to said body within the said groove; a cylinder member within said groove, and means for detachably securing said member toy said body, a shaft provided at one end with screw-threads for threaded engagement with the threads of the block, said shaft provided at the other end with a piston portion received Within said cylinder, and a cutter roller eccentrically mounted upon said shaft, the relationship being such that fluid passed through said watercourse and admitted into said cylinder will actuate the piston in one direction -I' to rotate said shaft through the threaded arrangement to in turn move the cutter roller outwardly of said groove.

HERMAN C. SMITH. 

